Liveweight‐productivity relationships in sheep

Abstract

Abstract An analysis of the breeding performance of sorne 11,258 sheep, mostly Corriedale, over aperiod of 15 years in relation to liveweight at mating has been made, yielding the following observations:‐ (i) Ewe and lamb mortality, 3.8 per cent and 12.0 per cent respectively, are independent of liveweight of the ewe, except at liveweights below 90–100 lb. (ii) Barrenness (mean 6 per cent) is relatively independent of liveweight above approximately 90–100 lb but below this critical weight barren (iii) Twinning increases approximately linearly with increasing liveweight at a rate of the order of 6 per cent per 10 lb. (iv) The lower breeding performance of 2‐tooth ewes in comparisonwith older ewes can be explained almost entirely in terms of liveweight at mating. The relative significance of liveweight and flushing as factors influencing lambing percentage are discussed.